1. Field of the Invention
The invention relates to a prop for a three-dimensional framework with a fastening device for fastening a railing device to the prop as well as to a connecting arrangement for a railing device, which comprises at least one prop for a three-dimensional framework and a railing device, which is fastenable to the prop with the help of a fastening device, and further relates to a method for fastening a railing device to a prop for a three-dimensional framework with the help of a fastening device.
2. The Prior Art
A number of fastening devices for fastening railing devices to props for three-dimensional frameworks, particularly to vertical scaffolding posts, have become known from practice in the past.
A particularly simple fastening construction has become known from, for example, CH-A-439679. This relates to a building scaffolding with vertical support frames, the vertical prop tubes of which are provided with U-shaped insertion eyes, into which insert ends, which are bent over downwardly at right angles, of handrail bars of railing frames are inserted. These railing frames are not secured against lifting up in upward direction, which from safety aspects is not acceptable.
Another railing fastening has become known from FR-A-25 16 141. There, scaffolding frames with vertical posts are provided, to which transverse bolts extending away therefrom are fastened. These have upwardly projecting dogs at the free ends thereof, so that these bolts form a kind of hook. The ends of a double railing or of a railing frame are hung in these hooks, for which purpose the upper two end straps of the double railing or railing frame are provided with downwardly open receiving openings forming a kind of counter-hook. The lower two end straps are provided with slots which extend in vertical direction, of which one slot is securable by a withdrawal securing means, which is pivotable about a horizontal axis, against withdrawal in the direction of the bolt of the associated hook of one of the scaffolding posts. These railings are similarly not secured against lifting off in upward direction. FR-A-25 16 141 also discloses L-shaped longitudinal bars used for connecting and fastening two adjacent scaffolding standing frames, on which L-shaped supports are supported, the supports being provided with a transverse bar on which scaffolding boards of wood can be supported in an intermediate position between the cross beams of adjacent scaffolding standing frames. These L-shaped longitudinal bars have two vertically spaced end limbs at their L-limb and a third end limb at their other end extending perpendicularly away from the L-limb. This third end limb has a downwardly open hook which can be hung in place on an upwardly open hook bolt of the post of one of the standing frames. The third end limb additionally has a hook-shaped pivot shackle which is pivotable about a transverse axis and which, when the third end limb is hung in place at the hook bolt, pivots under the hook bolt due to gravitational force and in this manner makes possible securing against lifting off in vertical direction at this end of the L-shaped longitudinal bar. Apart from the fact that faulty functioning in the case of dirtying can arise with this pivot shackle, which is not acceptable from safety aspects, this means an increased risk of injury at pivot shackles, which are fastened to the end of the L-shaped longitudinal bar, during handling of the L-shaped longitudinal bar.
Due to the aforesaid reasons other solutions have been developed by which it has been sought to avoid the afore-described disadvantages. These solutions can be essentially divided into two main groups.
A first main group relates to constructions in which the railing devices are secured in force-locking manner by clamping forces against lifting-off from the mounts of the supports. For that purpose, U-shaped wedge cases are usually fastened to the vertical scaffolding tube uprights by their limbs, into which straps, which are bent over downwardly at right angles, of railings are inserted and fastened thereat by means of a wedge. This has to be knocked in by a hammer in order to achieve compressing of a strap of a railing against the tubular upright or of two straps, which are hung in the same wedge case, of two railings against one another and against the tubular upright in order to thus fasten the railing or railings to be secure against vertical lifting-off in upward direction. In order to dismantle the scaffolding the wedges have to be knocked out by a suitable tool, so that the assembly and disassembly of scaffolding of that kind is only possible with a comparatively high degree of effort by means of a tool. Constructions of that kind have become known from, for example, DE-A-27 57 189, DE-A-38 32 480, DE-A-31 08 020, DE-A-198 27 284 and DE-U-20 2004 007 550 under the name ‘Layher-Blitz-Gerust-System’. For specific instances of use the wedge cases can also be detachably connectible with the scaffolding posts, as disclosed in, for example, WO 02/066765 A2.
Other clamping connections by which it is sought, by a force-locking connection, to prevent or impede lifting-off of the railing in upward direction have become known from, for example, DE-PS-100 10 229 or DE-PS-199 19 358. However, due to the comparatively limited clamping forces, lifting-off of the railing in upward direction cannot be securely prevented.
Further clamping connections in which, through a frictional clamping of one or two insertion straps, which are inserted into a U-shaped stirrup, of railings to the scaffolding post, a fastening of the railing to the scaffolding post also against vertical lifting-off is achievable have become known from, for example, DE-A-42 34 473 and DE-A-195 04 038. In these constructions the clamping of the railing strips, which are bent over downwardly at right angles, relative to the scaffolding post is achieved with the help of an eccentric lever pivotable about a horizontal transverse axis. In these clamping constructions comparatively large clamping forces have to be applied in order to secure the railings against lifting off in upward direction, which requires correspondingly high operating forces during locking and unlocking. Moreover, the use possibilities of these constructions are confined to horizontal scaffolding attachments in which the railings can be installed only from the same scaffolding tier, which can mean a safety risk.
A second main group of railing fastening constructions concerns solutions in which the railings are connected with the scaffolding posts in purely mechanically positive manner.
In a first subgroup, for this purpose cross bolts onto which the railings provided with matching passage holes are plugged are fastened to the vertical scaffolding props to produce transversely to the longitudinal axes thereof. The first subgroup can be subdivided into two further groups:
In a first group of this first subgroup of the second main group use is made of cylinder bolts which have at the free ends thereof a vertical slot in which a tilt pin strap is arranged to be pivotable about a horizontal transverse axis. For fastening of a railing to the scaffolding posts the tilt pin straps have to be transferred into an unlocking setting enabling introduction of the railing strips, which are provided with matching passage holes, onto the cylinder bolts. After the introduction and plugging on of the apertured railing strips the respective tilt pin strap has to be transferred back into a vertical locking setting, which in principle is achieved by itself with gravitational force assistance. However, if—as frequently occurs in practice—the free ends of the cylinder bolts are contaminated, for example by paint, faulty functions can arise so that the tilt pin straps concerned then have to be laboriously locked again by hand. This means an unacceptably high amount of effort or, for the case of inattention, a significant safety risk. Constructions of that kind have become known from, for example, DE-U-87 11 664, DE-A-31 39 980, DE-A-197 03 558 and DE-A-10 2004 055 394.
A second group of the first subgroup of the second main group concerns similar constructions which are thus based on the same fundamental principle, namely fastening to scaffolding posts transversely protruding bolts onto which railings provided with passage holes are plugged. However, in these constructions, such as have become known from, for example, DE-A-196 33 092 or EP-A-1 262 611, use is not made of pivotable tilt pin straps. In these fastening constructions the inner contour of the passage holes of the railings and the outer contour of the bolts receiving these are formed to be matched to one another in such a manner that plugging of the railings onto the bolts is possible only obliquely from below, i.e. from the scaffolding tier disposed thereunder, in that the railing is plugged from below onto the bolt at an angle of less than 90 degrees relative to the longitudinal axis of the scaffolding post. Subsequently, through pivoting of the railing upwardly into a horizontal use or installation setting a mechanically positive locking of the railing relative to the scaffolding post also in the direction of the longitudinal axis of the plug-on bolt is achieved at the same time. A horizontal mounting of railings from the same scaffolding tier is not possible with these constructions.
An intermediate variant of the second main group has become known from DE-A-10 2004 055 394 already mentioned in the foregoing. In this construction, which is now again provided with tilt pivot straps, the railing ends are provided with slots which extend radially outwardly from the plug-through opening for the cylinder bolts and are arranged at specific angles relative to the longitudinal axis of the railing and which enable insertion of tilt pin straps and plugging-on of the railing end also from the scaffolding tier disposed thereunder. After plugging of the railing from below onto the tilt pin straps and onto the cylinder bolts a mechanically positive locking also in the direction of the transverse bolt is again, achieved by pivoting the railing upwardly into its horizontal use or installation setting.
All these constructions associated with the first subgroup and the intermediate variants of the second main group have, however, the disadvantage that when the ends of two railings are plugged onto the bolts the rearward railing, thus that lying closer to the scaffolding post, cannot be demounted without the front railing, thus that lying further away from the scaffolding post, also being demounted beforehand.
Another construction concerning a railing fastening, which can be associated with a second subgroup of the second main group, in which the railings are similarly connected in purely mechanically positive manner with the scaffolding posts, has become known from DD 90 210 A. In that case a strap is welded to a tubular post which, with formation of a receptacle for railing strips to be inserted vertically, is profiled in L-shaped manner and bent over upwardly as well as open upwardly. In the region of the upper free end of the L-strap this is provided with a vertical slot. Projecting through this vertical slot is a nose of a drop latch which is pivotable about a horizontal pivot axis and which is rotatably mounted on a horizontal pin. The pin is welded to the L-strap with bridging-over of the vertical slot thereof. For the purpose of fastening two railing strips or in a given case also only one railing strip to the tubular post these are or this is introduced, vertically from above, vertically downwardly into the receptacle formed by the L-strap. The nose of the drop latch is thereby pivoted away into a release setting. In the course of a further introduction of the respective railing strip this is introduced vertically downwardly until the nose of the drop latch pivots, under gravitational force, back into its initial setting. Then or thereafter the respective railing strip comes to rest on the lower L-limb of the L-strap. For removal of the two railing strips or in a given case also only one of the railing strips the drop latch has to be manually pivoted upwardly about its pivot axis into a release setting making it possible to pull out the respective railing strip vertically upwardly, whereupon the respective railing strip can be pushed vertically upwardly out of the railing receptacle formed by the L-strap.
In this railing fastening it is necessary, due to the construction, to provide between the upper edges of the railing strips to be secured and the nose—which secures these against vertical lifting-off—of the drop latch an appropriately large gap enabling pivotation of the nose of the drop latch. As a result, the railing strips can be fastened only very loosely and with considerable vertical play, which means a safety risk. Moreover, this construction, due to the drop latch protruding laterally in the locking setting, requires a comparatively large amount of space and the risk exists that persons are caught at the drop latch. Finally, the risk exists that the upwardly open L-strap under the rough conditions in practice twists outwardly away from the tubular post so that then the railing strips are no longer secured against vertical lifting off. This means a significant safety risk.